Thumb rings of this general type are used especially in those endoscopic devices comprising medical instruments actuated with one hand. Illustratively, such may be resectoscopes operating with a high-frequency driven cutting loop, but also they may be optical urethrotomes or the like.
As a rule, a thumb ring for this kind of apparatus constitutes that part of a handle with which the medical instrument is actuated in a one-handed manner. The other part comprises a mating grip mounted on the instrument at a gripping distance from and distally from the thumb ring. Almost always, the thumb ring is affixed at one site of the instrument so as to be rotatable about an axis which is parallel to the longitudinal instrument axis. As a result, the surgeon may freely select that angular position of the thumb ring which is convenient for him.
The medical instrument is operated by relatively displacing the thumb ring and the mating grip in an axial direction relative to the instrument axis. Accordingly, as regards the known endoscopic implements, either the thumb ring or the mating grip may be stationary while the other part of the grip is then movable.
In order to hold the instrument, the surgeon inserts his thumb into the thumb ring and by means of at least one of the remaining fingers seizes the mating grip which usually comprises two grip components laterally projecting from the instrument. The surgeon can reliably hold the instrument by one hand and also (again one-handedly) he can actuate the medical instrument therein. To provide the surgeon with adequate actuating reliability, however, the thumb must be relatively firmly affixed into the thumb ring. Only then is it possible for the surgeon reliably to hold the instrument and only then can the handle be driven with adequate accuracy. But conventional thumb rings may press into the sensitive top thumb side in this process and cause painful pressure. The surgeon may be unpleasantly affected during and after prolonged use of the instrument.